Months later, the first high-profile cabinet scandal rocked the McGuinty ministry as Greg Sorbara resigned as Minister of Finance October 12, 2005, when it was revealed that he was named as a target in the criminal fraud investigation by the RCMP of Royal Group technologies Inc.[3] Dwight Duncan took over from Sorbara as Finance Minister.

[5] In a shuffle involving two other cabinet members,[6] Kennedy ultimately failed to secure leadership of the federal Liberal Party.

McGuinty recovered a valued colleague when Greg Sorbara was cleared of fraud charges and restored to his role as Minister of Finance on May 23,.

[7] In a minor shuffle involving only two other cabinet members, a new porfolio was created: On September 18, Joseph Cordiano stepped down as Minister of Economic Development and Trade, retiring from the ministry and from parliament for personal reasons.

[8] Days later, September 21, McGuinty named George Smitherman to the until-now vacant post of Deputy Premier.

[15] A new portfolio would be created: A second small shuffle occurred September 18, 2008, when, in an effort to confront Ontario's sagging economy and shrinking manufacturing sector during the Great Recession[16] McGuinty reorganised several ministerial portfolios: Three other established cabinet ministers were involved in the September 18 shuffle.

Ambitious high-profile minister Michael Bryant was eased out of cabinet, surrendering first his position as House Leader to his deputy Monique Smith February 4, 2009, and later stepping down as Ministry of Economic Development on May 25.

On November 9, he resigned from his post as Minister of Energy and Infrastructure and Deputy Premier of Ontario to run for mayor of Toronto.[20].

Days before the big mid-term cabinet shuffle January 18, 2010,[21] Jim Watson resigned from his post as Minister of Municipal Affairs and Housing to run for mayor of Ottawa.

[17] He became the second cabinet member to resign to pursue the mayoralty of a major Ontario city; unlike Smitherman, Watson would be successful and was elected mayor of Ottawa later in the year.

The final newly appointed cabinet minister to join the McGuinty ministry was Charles Sousa, brought on December 7 to replace Peter Fonseca at Ministry of Labour, who resigned[23] The 2011 Ontario general election resulted in the loss of 17 Liberal seats, leaving McGuinty one seat shy of a majority in Parliament.

Dalton McGuinty announced his retirement as Premier October 15, pending the election of a new Liberal Party leader.